The present invention relates to self-ballasted fluorescent lamps.
Fluorescent lamps, which have lower power consumption and a longer life than light bulbs, have become the subject of interest in recent years as energy-efficient light sources for homes and hotels, for example, because they are better for the global environment and more economic, and the ease with which they can be used as a substitute for light bulbs in lighting fixtures employing light bulbs without requiring any changes has lead to their increasingly widespread use.
Moreover, in addition to conventional self-ballasted fluorescent lamps with electrodes, electrodeless self-ballasted fluorescent lamps have recently also started to become widespread. Because they lack electrodes, electrodeless fluorescent lamps have a 5 to 10 times longer lamp life than fluorescent lamps with electrodes, which are the major factor that determines the lamp life in conventional fluorescent lamps with electrodes, and as a result they are expected to become even more widespread in the future.
To produce the most suitable lighting environment to correspond to the TPO, light is dimmed using the light bulb. A light bulb is normally dimmed through the use of a light bulb dimmer that controls the phase of the alternating current commercial power source in order to control the power that is input to the light bulb and change the brightness. However, when a self-ballasted fluorescent lamp is connected to an ordinary light bulb dimmer, there is a significant increase in the current that is input to the self-ballasted fluorescent lamp compared to when it is not connected to a light bulb dimmer, so that when the light bulb dimmer is operated the current may increase twofold or more.
Therefore, when a self-ballasted fluorescent lamp is connected to a light bulb dimmer, the stress on the electric components due to this increase in input current can significantly shorten the life of the ballast circuit.
This makes it difficult to ensure the reliability of a self-ballasted fluorescent lamp when it is inserted into the socket of a lighting fixture provided with a light bulb dimmer and used, and thus there is a need for technology to solve this problem.
A prior art related to this issue is disclosed in JP H09-129383A, which reports a discharge lamp ballast circuit device and a small scale discharge lamp including this circuit device. In its ballast circuit for operating the discharge lamp, the circuit device is provided with a means for detecting that the current input to the ballast circuit is a periodic current pulse that has a larger amplitude than the applied value, and with a means for blocking the supply of power to the ballast circuit based on the signal detected from said detection means.
FIG. 6 shows the circuit device of the discharge lamp disclosed in JP H09-129383A. As shown in FIG. 6, the circuit device disclosed therein is provided with a rectifier circuit D1 to D4, a storage means constituted by a capacitor C2 joined to the rectifier circuit D1 to D4, a DC/AC converter III for converting DC power from the rectifier circuit D1 to D4 into AC power and supplying it to a lamp LA, a means I(R1 to R6, T1, T2, C1) for detecting a periodic current pulse that has a larger amplitude than an applied value W1, and a means II(IIA, S1) joined to the means I, which alters/stops the state of operation of the circuit device.
When a power source is connected between K1 and K2, the voltage from the rectifier circuit, which is constituted by a resistor R7 and a diode bridge made of diodes D1 to D4, is smoothed out by the capacitor C2 and the direct current from the capacitor C2 is converted into alternating current at the DC/AC converter III and supplied to the lamp LA. If this circuit device were carelessly or otherwise connected to a commercial power source via a light bulb dimmer, then a pulse current with a larger amplitude than if it were not connected via the dimmer would flow periodically. As a consequence of this large amplitude pulse current, the amplitude of the voltage pulse generated in the resistor R6 is increased, the transistor T2 becomes conducting in response to the signal from the resistor R6, and as a result the transistor T1 also becomes conducting and the capacitor C1 is charged by the auxiliary power source (not shown), which is connected to the K3, via the resistor R3 and the transistor T1. The charge in the capacitor C1 is discharged through the resistor R4, however, if the current pulse is larger than the given value W1, the amount of charge that is charged from the auxiliary power source via the terminal K3 is larger than the amount of charge that is discharged via the resistor R4, and as a result the voltage is stepped up at both ends of the capacitor C1 and reaches the value for activating the circuit portion IIA of the means II. When this occurs, the circuit portion IIA puts the switching element S1 into an off state, and supply of the voltage is blocked.
However, with the circuit device shown in FIG. 6, even if the fact that the circuit device has been connected to the light bulb dimmer is detected by the means I for detecting periodic current pulses and the switching element S1 subsequently is turned off, there is a risk that the switching element S1 cannot be maintained (latched) in an off state. In other words, even if the switching element S1 is turned off, power is necessary to latch the switching element S1 in an off state, and if the auxiliary power source is provided at a stage after the rectifier circuit D1 to D4, then the voltage of the auxiliary power will gradually decrease because the line for supplying power to the auxiliary power source is blocked after the switching element S1 is turned off, and thus it is conceivable that the switching element S1 will eventually turn back on. The switching element S1 will then be repeatedly turned on and off, which will cause the lamp LA to repeatedly flicker. The auxiliary power source would be able to latch the switching element S1 in an off state if a rectifier circuit D1 to D4 other than the output power portion of the rectifier circuit D1 to D4 were provided, however, such a configuration would increase the size of the circuit device and would also be disadvantageous in terms of cost.
Also, the circuit device disclosed in JP H09-129383A is configured so that the supply of power to the circuit is always blocked when a self-ballasted fluorescent lamp has been inadvertently connected to a lighting fixture provided with a light bulb dimmer. In the case of a home, however, if the fluorescent lamp could continue to be operated at a maximum level of the dimmer, that is, without being dimmed, even if the lamp were used in this way, a new lighting fixture would not have to be purchased, which is preferable not only in terms of convenience but is also economical.
Also, when a self-ballasted fluorescent lamp does not operate because it has been inadvertently connected to a lighting fixture that is provided with a light bulb dimmer, a lamp that makes it clear to the user whether it is not operated because it has burnt out or because it has been connected to a light bulb dimmer is desirable.
The present invention is for solving these problems, and provides a self-ballasted fluorescent lamp provided with a function for operating normally when the self-ballasted fluorescent lamp is inadvertently connected to a lighting fixture provided with a light bulb dimmer if the dimmer is at the maximum level, and for detecting an increase in input current and reliably stopping operation of the ballast circuit if the dimmer is in a dimmed state, so as to latch the lamp in an unlit state and protect the ballast circuit.
It is a further object of the present invention to provide a self-ballasted fluorescent lamp capable of displaying via a display element, so that when the self-ballasted fluorescent lamp is inadvertently connected to a lighting fixture provided with a light bulb dimmer and does not operate, it can be made clear to the user that the self-ballasted fluorescent lamp is not operated because it has been connected to a commercial power source via a light bulb dimmer.
A first self-ballasted fluorescent lamp according to the present invention is provided with a lamp base for electrically connecting to a power source, a rectifier circuit for converting alternating current that is input from the lamp base into direct current, a smoothing capacitor that is connected to the rectifier circuit, an inverter circuit for converting direct current from the smoothing capacitor into a high frequency, a current detection circuit for detecting current from the rectifier circuit, and a stop circuit for stopping operation of the inverter circuit if the current that is detected by the current detection circuit exceeds a predetermined current value and maintaining the inverter circuit in that stopped state.
It is preferable that the predetermined current value is set to a value higher than a current value detected when the self-ballasted fluorescent lamp is electrically connected to a light bulb dimmer and is operated at substantially the maximum level.
It is further preferable that the inverter circuit includes at least one switching element and a control circuit that generates a signal for making the switching element alternately conducting and non-conducting, wherein the stop circuit includes a thyristor circuit that includes a portion that functions as a thyristor and that is conducting in response to a signal from the current detection circuit and a transistor for making the switching element non-conducting in response to a signal from the thyristor circuit, and when the current detected by the current detection circuit exceeds the predetermined current value, the thyristor circuit is made conducting in response to the signal from the current detection circuit, the transistor is made conducting by the signal from the thyristor circuit, and the switching element is maintained in a non-conducting state so as to maintain a luminous bulb in an unlit state.
In a preferable embodiment, the inverter circuit includes two FETs configuring a complementary circuit, as the at least one switching element, and the transistor shorts gate and drain of the higher voltage side FET to make it non-conducting.
It is preferable that the thyristor circuit includes a thyristor element as the portion that functions as a thyristor.
It is further preferable that the thyristor circuit includes a circuit made of two transistors as the portion that functions as a thyristor.
It is further preferable that the current detection circuit includes a current detection resistor disposed between the rectifier circuit and the smoothing capacitor and a current detection transistor that is connected in parallel with the current detection resistor and that is conducting when a voltage applied to the current detection resistor exceeds a predetermined value, wherein a signal from the current detection transistor serves as the signal from the current detection circuit and makes the thyristor circuit conducting.
It is further preferable that the rectifier circuit has a thermistor having a negative temperature coefficient, and that the thermistor functions as the current detection resistor.
It is also preferable that a display element that displays when the current detected by the current detection circuit has exceeded a predetermined current value is further provided.
A second self-ballasted fluorescent lamp according to the present invention is provided with a lamp base for electrically connecting to a power source, a rectifier circuit for converting alternating current that is input from the lamp base into direct current, a smoothing capacitor that is connected to the rectifier circuit, an inverter circuit for converting direct current from the smoothing capacitor into a high frequency, a voltage waveform detection circuit for detecting an input pulsating voltage waveform at both ends of the smoothing capacitor, comparing the pulsating voltage waveform with a reference voltage waveform, and outputting a control signal, and a stop circuit for stopping operation of the inverter circuit based on the control signal and maintaining the inverter circuit in that stopped state.
It is preferable that the reference voltage waveform is a voltage waveform when the alternating current input from the lamp base is a commercial power source, and that the stop circuit determines whether the alternating current input from the lamp base is alternating current that has been phase controlled by comparing it to the reference voltage waveform and outputs the control signal.
It is further preferable that the voltage waveform detection circuit is configured by a differential circuit that includes at least a first capacitor and a first resistor, and a series circuit of a second capacitor and a diode for detecting that there is a difference between the voltage waveform at both ends of the smoothing capacitor and the reference voltage waveform through a voltage that is applied to both ends of the first resistor.
It is further preferable that the stop circuit includes a thyristor circuit that includes a portion that functions as a thyristor and that receives a signal from at least the second capacitor of the voltage waveform detection circuit and becomes conducting, and a second resistor for holding the thyristor circuit in a conducting state.
It is additionally also preferable that the inverter circuit includes two FETs configuring a complementary circuit as the at least one switching element, and that the stop circuit is capable of shorting gate and drain of the higher voltage side FET to make it non-conducting.
It is preferable that the thyristor circuit includes a thyristor element as the portion that functions as a thyristor.
It is further preferable that the thyristor circuit includes a circuit made of two transistors as the portion that functions as a thyristor.
It is also preferable that a display element for displaying that the stop circuit has operated is further provided.
It is preferable that the size of rated values of components making up the voltage waveform detection circuit are set to predetermined values so that a current that makes the thyristor circuit conducting is supplied when the control signal is larger than a predetermined value.
It is further preferable that a luminous bulb of the self-ballasted fluorescent lamp is a luminous bulb with electrodes.
It is further preferable that a luminous bulb of the self-ballasted fluorescent lamp is an electrodeless luminous bulb.
A fluorescent lamp operating device according to the present invention is provided with a bulb, into which light emitting gas has been filled, and a ballast circuit for operating the bulb, wherein the ballast circuit includes an AC/DC conversion circuit for converting alternating current voltage into direct current voltage, a DC/AC conversion circuit for converting the direct current voltage converted at the AC/DC conversion circuit into alternating current voltage, a load resonance circuit that is electrically connected to the DC/AC conversion circuit, a detection circuit for detecting whether the alternating current voltage applied to the AC/DC conversion circuit is alternating current voltage that has been phase controlled by a dimmer, and which does not output a stop signal if the alternating current voltage is a commercial power source that has not been phase controlled or if the phase of the alternating current voltage is kept at a state of substantially the maximum level, but does output a stop signal in all other cases, and a stop circuit that stops operation of the DC/AC conversion circuit in response to the stop signal from the detection circuit and keeps the DC/AC conversion circuit in that stopped state.
It is preferable that the detection circuit has a means for detecting current and that it outputs the stop signal in accordance therewith.
It is further preferable that the detection circuit has a means for detecting voltage waveform and that it outputs the stop signal in accordance therewith.
It is further preferable that the fluorescent lamp is configured as a self-ballasted fluorescent lamp in which the bulb, the ballast circuit, and a lamp base that is electrically connected to the ballast circuit are formed into a single unit.
It is further preferable that a cavity portion into which an induction coil has been inserted is provided in the bulb, that the induction coil is included in the load resonance circuit, and that a frequency generated by the DC/AC conversion circuit is 40 to 500 kHz.